Nondriven, braked carrying chassis (individual or double-axle carrying chassis), which use so-called loose wheel axles to allow a low floor even in the area of the chassis, have been known from FIGS. 6 and 8 of the article "Neues bei Laufwerkskomponenten und gummigefederten Radern" New Developments in Chassis Components and Rubber-sprung Chassis! published in the journal Der Nahverkehr, No. 6/94. The loose wheel axle comprises essentially a nonrotating axle (portal axle) bent at right angles with bilateral axle heads with axle stubs, on which a usually rubber-sprung loose wheel each is mounted. The chassis frame of the chassis is supported on the loose wheel axle via a primary spring system. For example, the loose wheel axle for the standard gauge has for this purpose two machined contact surfaces for the primary spring system at the axle head on the inner side of the wheel. Even though the loose wheel axles of the above-mentioned designs are equipped with a disk brake, they have no possibility for driving.
Driven loose wheel axles of this type on a double-axle chassis for rail-borne vehicles have been known from DE 44 29 889 A1. A practical embodiment for this is shown, e.g., in the article "Combino, die modulierbare Niederflurstra.beta.enbahn . . . " Combino, the Low-Platform Street Car that Can be Modulated! published in the journal Verkehr und Technik, No. 9/96, pp. 387 ff. A chassis frame is supported here on two loose wheel axles (portal axles) bent at right angles, wherein the primary spring system connecting the contact surfaces for the chassis and axles is located on the inside of the wheels.
The drive to transmit the torque of the loose wheels of the loose wheel axles takes place in the form that a cardanic double coupling, which acts on the outer side of the wheel, is arranged between the primarily sprung, electromechanical drive arranged on the outer side of the vehicle and the corresponding loose wheel.
The design of the loose wheel axles with cardanic double coupling acting on the wheel and connections located on the inside for the primary spring system usually makes it possible, e.g., in the case of standard-gauge vehicles (gauge about 1,435 mm) to arrange a low-platform central aisle between the heads of the loose wheel axle with a sufficient width.
The width of the central aisle of the low-platform car is additionally further limited in an undesired manner due to the arrangement of the contact surfaces for the primary spring system on the inner side of the wheel in the case of vehicles with narrower gauge (e.g., for narrow-gauge railways with a gauge of 1,000 mm), in which the distance between the inner surfaces of the wheels is shorter. This also applies to, e.g., standard-gauge vehicles in which a greater central aisle width is desired than is made possible by the above-mentioned solution.